Modern rotorcraft, such as helicopters, include a plurality of rotor blades coupled to a central rotor hub assembly. When the rotor hub assembly stops or rotates at low speed, the lift and centrifugal forces on the rotor blades are less than the weight and stiffness of the blades. As such, the blades tend to droop downwardly. When the rotor hub assembly rotates at normal operating speeds, the lift and centrifugal forces overcome the weight and add to the stiffness of the blades thereby eliminating much of the droop.
To control the droop of the rotor blades in both the static and dynamic states just described, most helicopters are equipped with upper and lower stops. Such upper and lower stops are sometimes referred to in the art as droop stop mechanisms. Prior art droop stop mechanisms have a significant drawback due to their complexity. For example, the droop stop mechanism used in the CH-47 rotor includes approximately fourteen components. The droop stop mechanism used in the AH-64 rotor includes approximately nine components. Such complex designs increase production costs due to piece-part pricing, add weight to the overall structure, and are difficult to install and maintain.
In view of the foregoing, it would be desirable to provide a droop stop mechanism for a rotor hub assembly having a minimum number of components while also providing multipositional stops for controlling both static and dynamic droop.